WASHINGTON -- It was a bare-knuckle U.S. presidential campaign featuring allegations of nefarious dealings with a Russian autocrat and claims that Washington elites conspired to keep an antiestablishment candidate out of the White House.

Hillary Clinton versus Donald Trump in 2016? Try the 1828 election pitting incumbent John Quincy Adams, whose was accused of prostituting his chambermaid to Russia's Tsar Alexander I in exchange for political favors, against Andrew Jackson, whose supporters claimed he was robbed of the presidency by a "corrupt bargain" four years earlier.

Mudslinging, of course, has been a part of American presidential elections for more than 200 years. In the 1800 election, after all, a newspaper opposing Thomas Jefferson warned that "murder, robbery, rape, adultery, and incest will all be openly taught and practiced" if he were elected.

But with the confluence of invective, allegations of past sexual misconduct, and visceral disdain between the two candidates, several historians say the current campaign, between Clinton, a former senator and secretary of state, and wealthy businessman Trump, has reached new lows in terms of placing character attacks ahead of issues.

"There's no question that this is the dirtiest race we've seen in modern American history. You'd have to go back to earlier times in our history to find a race quite like this," Allan Lichtman, a professor of political history at American University who has correctly predicted the winner of the popular vote in every U.S. presidential election since 1984, told RFE/RL.

The perception of the campaign as a race toward the gutter is due largely to Trump and his raucous and rapid political rise, according to presidential historians interviewed by RFE/RL.

A brash real-estate developer and former reality-TV star who has never held elected office, Trump has embraced trash-talking and shunned political decorum like no other U.S. presidential candidate in modern history.

In addition to the personal insults he has hurled at Clinton, journalists, and an array of critics, Trump has threatened to jail his Democratic rival if he is elected and refused to say he would recognize the outcome as legitimate if he loses.

"I've never seen a candidate in my lifetime who was as vulgar, as abrasive, as crude. You know, Richard Nixon was pretty bad, but these were on tapes that were hidden that were not part of the public conversation," said Robert Dallek, a U.S. presidential historian and author of an acclaimed biography of President John F. Kennedy.

'Most Depressing Election'

This style has arguably burnished his reputation as an outsider capable of upending politics-as-usual in Washington. In a New York Times/CBS poll in September, 48 percent of respondents said that Trump could "bring about real change in the way things are done in Washington," compared to 36 percent for Clinton, a former first lady, U.S. senator, and secretary of state.

Clinton is no stranger to rough-and-tumble politics, and operatives working for her campaign were recently caught discussing how to stir up violence and mayhem at Trump rallies by using undercover provocateurs.

And while she has repeatedly sought to portray herself as above the melee in the mud, her campaign has repeatedly seized on fodder provided by Trump in its effort to paint him as unfit for the highest office in the land -- most notably a leaked 2005 video in which Trump is heard making lewd comments about women suggesting predatory behavior, and a series of accusations by women who say the Republican nominee sexually assaulted them.

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While important issues such as immigration, tax policy, and national security have not been entirely absent from the campaign, the battle for the White House between Clinton and Trump has for a potentially crucial segment of voters turned into a referendum on the candidates' respective characters.

"It's one of the most bitterly fought and, I would say, in terms of addressing the issues that face this country, it's one of the most depressing elections in my lifetime and maybe in the whole history of the two centuries of this republic," says David Kennedy, a Pulitzer Prize-winning professor of U.S. history at Stanford University.

'No Regard' For Normal Conventions

David Greenberg, a professor of history, journalism, and media studies at Rutgers University, disagreed with assertions that issues have taken a backseat to mudslinging in the run-up to the November 8 election. Trump, he said, is an "issue-driven" candidate, with his hard-line stance on immigration and promise to build "a great wall on the southern border" at the forefront.

He drew comparisons with the election in 1800, when supporters of Jefferson accused his opponent, John Adams, of having a "hideous hermaphroditical character, which has neither the force and firmness of a man, nor the gentleness and sensibility of a woman."

Adams' backers, meanwhile, responded with a racially charged leaflet describing Jefferson as "a mean-spirited, low-lived fellow, the son of a half-breed Indian squaw, sired by a Virginia mulatto father."

"In 1800, there were real issues at stake underneath the rhetoric, and it was kind of not hard to see that even though it took a personal form, Americans were arguing about questions like what kind of an economy they wanted, what kind of national government and freedoms versus central planning they wanted, [and] major issues in foreign policy," Greenberg told RFE/RL.

He said the malicious tone openly embraced by Trump personally is merely an "intensification of this negativity" that has long pulsated through U.S. presidential elections.

"[Trump] has taken the rhetoric and the posture of being an outsider coming to blow up the Washington establishment to such an extreme -- and he's embodied that in such an extreme way -- that he has shown kind of no regard at all for the normal conventions of politics," Greenberg said.

"It's rare for the candidate himself to be so unconcerned with being statesmanlike," he added.

'Nasty Woman' And Kremlin 'Puppet'

Clinton has launched fierce broadsides at Trump throughout the campaign as well, of course, perhaps most relentlessly concerning his treatment of women following the leaked audio featuring his lewd comments and the accusations of sexual assault, which Trump vehemently denies.

This line of attack, said Dallek, was likely "irresistible" to Clinton, a political veteran who over the past three decades has survived myriad political and sex scandals involving her husband, former President Bill Clinton, before becoming the first female candidate for a major party in a U.S. presidential election.

Clinton has also hammered Trump over the cyberattacks and e-mail leaks targeting the Democratic National Committee and prominent current and former American political figures that have embarrassed her party and which Washington has officially accused the Russian government of orchestrating.

In their third and final debate, Clinton accused Russian President Vladimir Putin himself of ordering the cyberattacks in order to help Trump, who has spoken favorably of the Russian leader and voiced a desire to ease battered bilateral ties with Moscow. Both Trump and the Kremlin have called accusations of a Russian cyberoperation to ensure his election absurd.

Compared to their previous two debates, the October 19 showdown was a more issue-focused affair. But the sniping and acrimonious rhetoric nonetheless surfaced throughout, with Trump at one point muttering into the microphone that Clinton is a "nasty woman."